[Histological evaluation of poly (dextrogyr-levogyr) lactide acid-triiodothyronine in sciatic nerve defect of rat].

OBJECTIVE: To make a histological evaluation of poly (dextrogyr-levogyr)lactide acid-triiodothyronine (PDLLA-T3) in sciatic nerve defect of rat. METHODS: Ninety SD rats were evenly divided into 3 groups (autograft group A, PDLLA-T3 group B and PDLLA group C). Group D was control group. The left sciatic nerves were cut off by operation and 1 cm-nerve-defect was set up. The specimens were collected 2 weeks, 1 month and 2 months after the operation respectively, simultaneously the right sciatic nerves were collected as normal control group D. HE staining, electron microscope, S-100 immunohistochemistry, and Bielschowsky staining were done in all the specimens, the quantity and quality of the regenerated nerves were observed, and all the results were processed by image analyzer. RESULTS: Two weeks after the operation,histological observation indicated that the materials in groups B and C were not completely degraded. Transmission electron microscopic observation showed that the myelin sheath was not thick and it was about 0.5 microm in thickness. There was no significant difference among the 3 groups. One month after the operation, histological observation indicated that in group A the regenerated nerves passed through the scaffold and in the new nerves there were regenerated blood vessels. The materials in groups B and C were not completely degraded. S-100 immunohistochemical observation and Bielschowsky staining showed that in group B PDLLA-T3 repaired the defect successfully and the regenerated nerve myelin sheath was 1.81+/-0.19 microm in thickness. The effect in group B was better than that of groups A and C (P> 0.05). Two months after the operation, the materials in groups B and C were completely degraded. The quantity of the regenerated nerves in group B confirmed by S-100 immunohistochemical observation and Bielschowslcy staining was more than that in group C(P<0.05) and close to that in group A. The regenerated nerve myelin sheath in group B was 2.15+/-0.27 microm in the thickness and was thicker than that in group C (P<0.05), but thinner than that in groups A and D (P<0.05). CONCLUSION: PDLLA-T3 can repair the defect of rat sciatic nerve with satisfactory quantity and quality of regenerated nerves.